Steering column for a motor vehicle

Abstract

The present invention relates to a steering column (1) for a motor vehicle, comprising a shell unit (3) in which a steering spindle (4) is rotatably mounted about a longitudinally extending longitudinal axis (L), and which has at least three longitudinally telescopically adjustable shell elements (31, 32, 33) comprising at least an inner shell (33), an outer shell (32) and an intermediate element (32) arranged between them, wherein a motorized adjustment drive (6) engages the shell elements (31, 32, 33), which has a first spindle drive (7) arranged between the inner shell (33) and the intermediate element (32), and a second spindle drive (8) arranged between the intermediate element (32) and the outer shell (31), wherein the first spindle drive (7) has a first threaded spindle (71) engaging in a first spindle nut (72) and rotatably driven relative thereto by a drive unit (6),and the second spindle drive (8) has a second threaded spindle (81) engaging in a second spindle nut (82) and rotatably driven relative to it by the drive unit (6). To improve the range of applications and enable a reduced installation space, the invention proposes that the first spindle nut (72) and the second threaded spindle (81) are coaxially connected to each other in a rotationally fixed manner to form a threaded unit (63) that is rotatably driven by the drive unit (6) and is axially supported relative to the drive unit (6).

Description

State of the art

[0001] The invention relates to a steering column for a motor vehicle, comprising a casing unit in which a steering spindle is rotatably mounted about a longitudinal axis extending in the longitudinal direction, and which has at least three longitudinally telescopically adjustable casing elements, which comprise at least an inner casing, an outer casing, and an intermediate element arranged therebetween. A motorized adjustment drive engages the casing elements, which has a first spindle drive arranged between the inner casing and the intermediate element, and a second spindle drive arranged between the intermediate element and the outer casing. The first spindle drive has a first threaded spindle engaging a first spindle nut and rotatably driven relative thereto by a drive unit about the threaded axis, and the second spindle drive has a second threaded spindle engaging a second spindle nut and rotatably driven relative thereto by the drive unit.wherein the first spindle nut and the second threaded spindle are coaxially connected to one another in a rotationally fixed manner to form a threaded unit which is rotatably driven by the drive unit and which is axially supported relative to the drive unit, wherein the outer shell is held by a support unit.

[0002] A steering column for a motor vehicle comprises a steering column housing in which a steering spindle is mounted for rotation about its longitudinal axis. At the rear end of the steering column, facing the driver, a steering wheel, for example, is attached as a manual steering input device. The steering column housing is held by a support unit attached to the vehicle body. By adjusting the steering column housing relative to the support unit, the steering wheel position relative to the vehicle body can be adjusted.

[0003] Longitudinal adjustment, in which the steering wheel can be adjusted backward or forward in the longitudinal direction relative to the driver's position, is made possible in this type of steering column by a telescopic design of the steering column unit and the steering spindle. Furthermore, the steering column can be collapsed longitudinally in the event of a crash, effectively preventing the steering column from penetrating the interior of the passenger compartment and causing occupant injuries.

[0004] The casing unit of a generic steering column has at least three casing elements that can be telescoped relative to one another, which are also synonymously referred to as telescopic elements or casing tubes. For example, a triple or multiple telescopic arrangement can be provided, with at least three or more casing elements that are telescopically nested within one another. These comprise at least one inner casing element, also referred to as the inner casing, inner casing element, or tube, which extends coaxially into at least one middle casing element or intermediate element, which in turn extends telescopically into an outer casing element, also referred to as the outer casing, outer casing element, or tube. By moving the casing tubes apart or together in the longitudinal direction, the casing unit and thus the steering column can be shortened or lengthened.

[0005] The steering column is adjusted by a motorized adjustment drive. This drive comprises a spindle drive arranged between relatively adjustable casing elements. The spindle is axially supported on one casing element and engages a spindle nut axially supported on another casing element that is adjustable relative to the other. The motorized drive unit allows the threaded spindle and spindle nut to be driven by an electric motor to rotate relative to each other about the thread or spindle axis, allowing the casing elements to move axially closer together or away from each other, depending on the direction of rotation of the drive.

[0006] For adjusting a multiple telescope arrangement, it is known from US 2019 / 0210633 A1 to provide a first and a second spindle drive, each of which engages two casing elements that can be adjusted relative to each other. This enables a flexibly preset, synchronized adjustment. However, the disadvantage is that the two spindle drives are complexly constructed and, regardless of the adjustment state, require a relatively large installation space that is fixed by the lengths of the threaded spindles. This can be particularly problematic in steering systems for self-driving vehicles, where the steering column must be able to be retracted into a stowed position outside the operating area in the most space-saving way possible during autonomous driving.

[0007] A steering column of the type mentioned above is known, for example, from DE 10 2015 224602 A1. WO 2021 / 049803 A1 describes a different design of the adjustment drive.

[0008] In view of the problems explained above, it is an object of the present invention to improve the possible applications and to enable a reduced installation space. Description of the invention

[0009] This object is achieved according to the invention by the steering column having the features of claim 1. Advantageous further developments emerge from the subclaims.

[0010] In a steering column for a motor vehicle, comprising a casing unit in which a steering spindle is rotatably mounted about a longitudinal axis extending in the longitudinal direction, and which has at least three longitudinally telescopically adjustable casing elements comprising at least one inner casing, one outer casing, and an intermediate element arranged therebetween, wherein a motorized adjustment drive engages the casing elements, which has a first spindle drive arranged between the inner casing and the intermediate element, and a second spindle drive arranged between the intermediate element and the outer casing, wherein the first spindle drive has a first threaded spindle engaging in a first spindle nut and rotatably driven relative thereto by a drive unit about the threaded axis, and the second spindle drive has a second threaded spindle engaging in a second spindle nut and rotatably driven relative thereto by the drive unit,wherein the first spindle nut and the second threaded spindle are coaxially connected to one another in a rotationally fixed manner to form a threaded unit which can be driven in rotation by the drive unit and which are axially supported relative to the drive unit, wherein the outer casing is held by a support unit, the invention provides that the drive unit is axially fixedly attached to an intermediate element.

[0011] According to the invention, the drive unit is axially fixedly attached to an intermediate element. The threaded unit according to the invention can be driven in rotation by the drive unit and is mounted with axial support. The first spindle nut, together with the first threaded spindle, forms a plunger spindle drive for adjusting a casing element axially adjacent to the intermediate element, for example the inner casing, relative to the intermediate element. The second threaded spindle, together with the second spindle nut, forms a rotary spindle drive for adjusting another casing element axially opposite and adjacent to the intermediate element, for example the outer casing, relative to the intermediate element. When the threaded unit is driven in rotation, simultaneous axial adjustment of the outer casing relative to the intermediate element and of the intermediate element relative to the inner casing can take place. The compact design according to the invention is advantageous in this regard.

[0012] The threaded unit forms a combined threaded spindle-spindle nut unit in which the first spindle nut and the second threaded spindle are functionally combined. The internal thread of the first spindle nut and the external thread of the second threaded spindle are arranged coaxially to the common thread axis, which is identical to the spindle axes of both spindle drives. This integrated threaded unit can be driven by the drive unit to rotate about the thread axis relative to the first threaded spindle and the second spindle nut, and is supported axially with respect to the thread axis on the drive unit.

[0013] It also includes designs in which the first and second spindle drive are interchanged with respect to the inner and outer casing, ie the first spindle drive is arranged between the outer casing and the intermediate element, or in which a spindle drive acts between two intermediate elements.

[0014] An advantage of the invention is that the two screw drives, each formed by the first and second threaded spindles and spindle nuts, are driven synchronously by the rotating drive of the threaded element according to the invention. Consequently, the synchronized adjustment of at least three casing elements coupled by the spindle drives is possible without additional synchronization devices. Furthermore, the drive coupling of the integrated threaded element to the drive unit is possible with less effort than with the separate spindle drives of the prior art. Accordingly, the adjustment drive can advantageously be designed to be more compact and less complex. Because only the one integrated thread unit can be driven in rotation, a structurally simple design and high functional and operational reliability can be achieved.

[0015] The advantageous, variably adaptable design options arise in particular from the fact that the first spindle drive is designed as a so-called plunger spindle drive, in which the first spindle nut is rotationally driven and the threaded spindle engaging therein is fixed in a rotationally fixed manner to the casing element that can be adjusted relative to the drive unit, and the second spindle drive is designed as a so-called rotary spindle drive, in which the second threaded spindle is rotationally driven and the spindle nut screwed onto it is fixed in a rotationally fixed manner to the casing element that can be adjusted relative to the drive unit. The drive unit is fixed to a third casing element that is axially fixed with respect to the two adjustable casing elements mentioned, and can drive the threaded element according to the invention optionally in both directions of rotation, whereby both spindle drives are forced to be driven synchronously.

[0016] The drive unit is attached to the shell unit on one of the shell elements.

[0017] An electric motor can be coupled to the threaded unit according to the invention via a gear, or directly, in order to drive it in rotation about the thread axis relative to the casing unit.

[0018] The shell unit comprises at least three telescopic shell elements, namely an outer shell, an inner shell, and at least one intermediate shell arranged in a nested manner between them, forming an intermediate element. The outer shell is held by a support unit connectable to the body.

[0019] The telescopic adjustment allows the inner shell and the intermediate shell, or all intermediate shells, to be adjusted relative to the support unit. The motor drive unit is attached to the intermediate shell or intermediate element, which is adjustable relative to the support unit.

[0020] It is essential that the first threaded spindle forms a fixed threaded spindle of a rotary spindle drive, which extends, for example, between the intermediate element (intermediate casing) to which the drive unit is attached, and one casing that is movable relative thereto, for example the inner casing, and the second threaded spindle forms the rotationally drivable threaded spindle of a rotary spindle drive, which extends between the intermediate element (intermediate casing) to which the drive unit is attached, and the other casing that is movable relative thereto, for example the outer casing, and engages in a spindle nut that is firmly attached to the outer casing. By rotating the threaded unit according to the invention, the intermediate element to which the drive unit is attached is adjusted relative to the inner and outer casings, and thus also moved relative to the support unit.Essential for this structurally advantageous kinematics is in particular the attachment of the drive unit to the intermediate element, which is adjustable relative to the outer casing held by the support unit.

[0021] The drive unit attached to the intermediate element is arranged outside this intermediate element. Accordingly, the threaded unit according to the invention and the first threaded spindle engaging therein are also arranged outside the intermediate element, with the thread axis running parallel to the longitudinal axis of the casing unit at a radial distance.

[0022] The thread axis of the coaxial internal and external threads of the threaded unit preferably runs parallel to the longitudinal axis of the jacket unit.

[0023] Preferably, the internal thread of the first spindle nut can be arranged within the external thread of the second threaded spindle. The internal thread can be arranged in the region of the axial extension of the second threaded spindle or axially adjacent to it. For example, the spindle nut can be coaxially mounted on the front side in an axial end region of the threaded spindle. This benefits a compact design.

[0024] Preferably, the second threaded spindle can be designed as a hollow spindle in which the first threaded spindle can be axially received. The hollow spindle has an axial passage with an opening cross-section that is, at least in sections, larger than the external cross-section of the external thread of the first threaded spindle. As a result, when the casing unit is retracted, the latter can be screwed through the first spindle nut and the section protruding from the spindle nut can insert axially into the second threaded spindle. In this way, the first threaded spindle can be stowed practically within the longitudinal extent of the hollow second threaded spindle, so that in a fully retracted stowed state, both spindle drives can be accommodated within a relatively short stowed length, which can essentially correspond to the length of the second threaded spindle.This is an advantage over the aforementioned state of the art, where the minimum stowage length is at least the sum of the lengths of both threaded spindles, even when stowed together.

[0025] An advantageous embodiment can provide for the threaded unit to be formed in one piece. At least the first spindle nut and the second threaded spindle can be formed as a single component, which has the internal thread of the first spindle nut and the external thread of the second threaded spindle. Advantages include a compact design with relatively low manufacturing costs and high functional reliability.

[0026] It is preferably possible for the threaded unit to be connected to a gear wheel of the drive unit. The drive unit comprises an electric motor whose motor shaft is coupled on the input side to a gear, which is connected on the output side to the threaded unit in order to drive the latter in rotation about the thread axis relative to the casing unit. Because the threaded unit is directly connected to or comprises an output-side gear element, such as a gear wheel, worm wheel, belt wheel, or the like, an efficient drive and a space-saving design integrated with the drive unit can be advantageously realized.

[0027] In a preferred embodiment, the gear wheel can be formed in one piece or integrally with the threaded unit. For example, the threaded unit can have a gear ring on its outer circumference, preferably in the region of the first spindle nut, which can engage with a driven gearing means of the transmission. For example, an integrated worm wheel can be formed in this way, into which a motor-driven worm engages. This enables efficient production, a small required installation space, and low weight.

[0028] It can be advantageous for the threaded unit to be made of a plastic. The first spindle nut and / or the second threaded spindle can each be made entirely or partially from a plastic, preferably at least in the area of ​​the threads. It is also possible for a gear wheel connected to the threaded unit to also be made at least partially from plastic, for example in the area of ​​a gear ring. One advantage is that a plastic in combination with a metal or another plastic can achieve favorable sliding properties and low friction, thereby enabling smooth and low-backlash adjustment. Furthermore, long-term, low-wear and essentially maintenance-free operation can be guaranteed.

[0029] Preferably, production can be carried out by plastic injection molding from a thermoplastic polymer. Preferably, the first spindle nut and / or the second threaded spindle can be manufactured as a single-piece injection-molded part. For the design as a gear wheel, a gear ring, for example, can be formed, which can also be integrated as a single piece in the injection molding or can be molded onto the threaded element. This enables a weight-saving design and advantageously efficient production.

[0030] The threaded unit can comprise a solid plastic part, preferably an injection-molded part, or a core element, which can, for example, comprise a metallic material, and which is at least partially surrounded by or coated with a plastic, for example in the area of ​​the threads and / or a gear wheel. Such a core element can preferably be overmolded with the plastic.

[0031] To reduce friction, the surface of the threaded unit can be designed to reduce friction, at least in the area of ​​the threads and / or a gear wheel. For this purpose, permanently self-lubricating coatings, hard material coatings, or the like can be applied, and alternatively or additionally, lubricant reservoirs can be provided, for example, lubricant pockets or the like molded into the surfaces, which can be filled with grease or solid lubricant.

[0032] With the same functional principle, the second spindle nut can alternatively be fixed to the inner casing or to another intermediate element, and accordingly the first threaded spindle can be fixed to the outer casing or to another intermediate element.

[0033] It is preferred that the first spindle drive and the second spindle drive have opposing threads. For example, the first threaded spindle and spindle nut can have a right-hand thread, and the second threaded spindle and spindle nut can have a left-hand thread. When the threaded unit is driven in a clockwise direction - clockwise when viewed axially from the threaded unit to the second spindle nut - the second spindle nut is then moved towards the threaded unit, and the first threaded spindle is moved axially opposite to this, also towards the threaded unit. Accordingly, the outer casing and inner casing are moved axially towards each other, towards the drive unit, so that the casing elements are moved together in the longitudinal direction, thereby shortening the casing unit. This advantageously allows for a simple, robust, and functionally reliable design.

[0034] Because the second threaded spindle is preferably designed as a hollow spindle, the first threaded spindle can be axially inserted into it when the casing unit is moved together, so that the two spindle drives can also be compactly stored inside each other when the casing unit is moved together.

[0035] By reversing the drive rotation direction, the second spindle nut and the first threaded spindle can be moved axially opposite to the threaded unit and thus away from the drive unit, so that the casing elements are extended apart in the longitudinal direction.

[0036] The arrangement of right-hand and left-hand threads can be reversed with regard to the spindle drives while maintaining the same effect.

[0037] It is possible for the first spindle drive and the second spindle drive to have different thread pitches. The thread pitch determines the adjustment range depending on the relative rotation of the threaded spindle and spindle nut, and accordingly, the adjustment speed depending on the drive speed. A large thread pitch corresponds to a relatively large linear adjustment range and a high adjustment speed, while a smaller thread pitch corresponds to a smaller adjustment range and a lower adjustment speed, but with a higher linear adjustment force.Because the threaded unit according to the invention, comprising the first spindle nut and the second threaded spindle, is driven by the drive unit through a predetermined angle of rotation at a predetermined speed, different adjustment paths and adjustment speeds can be achieved by the different thread pitches for the two spindle drives with a predetermined drive. This advantageously allows a type of asymmetrical adjustment to be achieved, which can be individually adapted. For example, casing elements with a larger cross-section can be extended further relative to one another by a first spindle drive during adjustment by a first adjustment drive than casing elements with a relatively smaller cross-section can be extended by a second adjustment drive in order to achieve the highest possible rigidity of the extended telescopic arrangement.Alternatively, relatively faster and wider adjustment of shell elements with a smaller cross-section is possible, thereby reducing the masses moved during adjustment. This enables faster adjustment and / or requires less drive power from the drive unit.

[0038] It is possible to attach a manual steering handle to the steering spindle.

[0039] This can, for example, be a steering wheel which can be fixed in a rotationally fixed manner to a connecting section at the rear end section of the steering spindle.

[0040] It may be advantageous for at least one of the spindle drives to be self-locking. This can be achieved by making at least one of the threads self-locking. This advantageously ensures that even high axial forces acting on the adjustment drive do not cause the set steering column adjustment to be altered. Description of the drawings

[0041] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. In detail: Figure 1 shows a steering column according to the invention in an extended adjustment state in a schematic perspective view, Figure 2 shows the steering column according to Figure 1 in a further perspective view, Figure 3 the steering column according to Figures 1 and 2 in an axial view, Figure 4 the steering column casing unit according to Figure 1in extended adjustment state (operating position) in a side view, Figure 5 the jacket unit in a side view as in Figure 4 in the retracted adjustment position (stove position). Embodiments of the invention

[0042] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

[0043] Figures 1, 2 and 3 show a steering column 1 according to the invention, in an at least partially extended operating position ( Figures 1 and 2 ), and in a retracted storage position ( Figure 3 ), The viewing direction is shown diagonally from the rear above in relation to the direction of travel ( Figure 1 ), or diagonally from the front ( Figure 2 ), or in the longitudinal direction, ie axially ( Figure 3 ). Figure 4 shows a side view in an extended operating position, and Figure 5 in a collapsed storage position.

[0044] The steering column 1 has an actuating unit 2. This comprises a casing unit 3, which has an outer casing 31, also referred to as the outer casing tube 31, an intermediate casing 32, also referred to as the intermediate element 32, and an inner casing 33, also referred to as the inner casing tube 33. These form casing elements 31, 32, and 33, which are arranged axially, in the axial direction of a longitudinal axis L, coaxially adjustable within one another, telescopically, as indicated by a double arrow.

[0045] A steering spindle 4 is mounted in the casing unit 3 so as to be rotatable about the longitudinal axis L and has in its rear end region a connecting section 41 for attaching a manual steering handle (not shown), for example a steering wheel.

[0046] The steering spindle 4 can also be designed to be telescopic for longitudinal adjustment. It is also conceivable and possible for the steering spindle 4 not to be axially continuous through the casing unit 3, but rather to interact with electronic rotation sensors of a steer-by-wire steering system in which the steering spindle has no direct mechanical connection to the steerable wheels. These rotation sensors can preferably be housed in the casing unit 3, for example, in the inner casing 33, in order to generate electrical control signals for controlling electric steering actuators interacting with the steerable wheels, depending on a manual steering input.

[0047] The casing unit 3 is held in a two-part support unit 5, which has fastening means 51 for attachment to a vehicle body (not shown).

[0048] An adjustment drive 6 according to the invention for telescopic longitudinal adjustment has a drive unit 61 that is fixed to the intermediate casing 32 and supported in the axial direction. The drive unit has an electric motor 62.

[0049] The adjustment drive 6 has a first spindle drive 7 and a second spindle drive 8.

[0050] Details of the adjustment drive 6 are in the Figures 4 and 5 which shows it in longitudinal section.

[0051] The first spindle drive 7 is designed as a so-called plunge spindle drive and comprises a first threaded spindle 71 which extends along a threaded axis S, also referred to as spindle axis S, which preferably runs parallel to the longitudinal axis L. The threaded spindle 71 engages in the internal thread of a first spindle nut 72 which, according to the invention, is firmly connected to a threaded element 63, preferably formed in one piece or in one piece.

[0052] The threaded element 63 is mounted in the drive unit 61 and is supported axially (with respect to the thread axis S) so that it can be driven in rotation about the thread axis S by the motor 62.

[0053] The threaded spindle 71 is axially supported and fixed at its free end region via a connecting element 73 on the inner casing 33 in a rotationally fixed manner with respect to the casing unit 3.

[0054] The second spindle drive 8 is designed as a so-called rotary spindle drive and comprises a second threaded spindle 81, which also extends along the thread axis S. The threaded spindle 81 is connected coaxially to the threaded element 63 in a rotationally fixed manner and can thus preferably be formed as a single piece or in one piece. Accordingly, according to the invention, the first spindle nut 72 and the second threaded spindle 81 are connected to one another coaxially with respect to the thread axis S in a rotationally fixed manner and axially fixed to form the threaded unit 63. The threaded unit 63 can be driven by the drive unit 61 to rotate about the thread axis S and is axially supported relative to the drive unit 61.

[0055] At its portion axially projecting from the threaded element 63, the second threaded spindle 81 has an external thread that engages a second spindle nut 82. This nut is axially supported on the outer casing 31 and fixed in a rotationally fixed manner.

[0056] In Figure 4 It is clearly visible how the internal thread of the first spindle nut 72 is formed coaxially within the threaded element 63. The first spindle nut 72 is fixedly attached axially to the end face of the second threaded spindle 81, preferably in a one-piece design, for example, made of a plastic.

[0057] The threaded element 63 is axially supported for rotation between thrust bearings 64 in the drive unit 61. These thrust bearings 64 can be designed as rolling bearings, for example as angular contact ball bearings in an X-arrangement or an O-arrangement.

[0058] On its outer circumference, preferably in the area of ​​the first spindle nut 72 mounted between the thrust bearings 64, the threaded element 63 has a gear ring 65. It is thus designed as a gear wheel, into which a gear wheel (not shown in detail) driven by the motor 62, for example a worm, engages. The gear ring 65 can preferably also be formed integrally with the threaded element, for example, by means of a plastic overmolding.

[0059] The function is based on the Figures 4 and 5 explained, whereby Figure 4 shows an operating position in which the casing elements 31, 32, 33 are extended in the longitudinal direction, and Figure 5 a stowage position in which the casing elements 31, 32, 33 are maximally moved together.

[0060] The two spindle drives 7 and 8 have opposing threads, for example the first spindle drive 7 can have a left-hand thread and the second spindle drive 8 a right-hand thread, or vice versa.

[0061] The second threaded spindle 81 is designed as a tubular hollow spindle that is coaxially attached to the first spindle nut 72. The open inner diameter of the second threaded spindle 81 is larger than the outer diameter of the external thread of the first threaded spindle 71. This allows the first threaded spindle 71 to be inserted coaxially into the second threaded spindle 81.

[0062] If, in the extended adjustment state, the threaded unit 63 is driven in rotation by the motor 62, for example axially, in Figures 4 and 5clockwise from the right, the second threaded spindle 81 is screwed into the second spindle nut 82. This moves the outer casing 31 towards the drive unit 61 and the intermediate element 32, as shown in Figure 4 is indicated by the right-pointing arrow. At the same time, the first threaded spindle 71 is screwed into the rotating first spindle nut 72 and moves together with the inner casing 33 toward the drive unit 61 and the intermediate element 61 connected thereto, as indicated by the left-pointing arrow.

[0063] Accordingly, the rotating drive of the threaded element 63 according to the invention, starting from the extended adjustment state according to Figure 4 a simultaneous actuation of the two axially counteracting spindle drives 7 and 8, so that the casing elements 31, 32, 33 are moved together in a synchronized manner.

[0064] The maximum retracted storage position is in Figure 5 This shows how the first threaded spindle 71 is almost completely axially inserted into the second threaded spindle 81, which is designed as a hollow spindle. This enables advantageous, particularly compact storage.

[0065] It is possible for the threads of the spindle drives 7 and 8 to have the same thread pitch, or to have different thread pitches in order to realize different adjustment paths between the casing elements 31 and 32 or 32 and 33 for a given rotating drive of the threaded element 63.

[0066] The threaded element 63, including the first spindle nut 72, the second threaded spindle 81, and / or the gear ring 65, can be made of a plastic material, or can be formed entirely from it, for example, as a plastic injection-molded part made of a thermoplastic polymer. The first threaded spindle 71 and the second spindle nut 82 can be made of a metallic material, for example, steel. This advantageously allows for a low-friction friction pairing.

[0067] It is essential to the invention that the drive unit 61 is attached to the intermediate casing 32, which is adjustable relative to the outer casing 31 and thus also relative to the support unit 5. Thus, the drive unit 61 is moved relative to the support unit 5 during adjustment. List of reference symbols

[0068] 1Steering column 2Adjustment unit 3Shell unit 31Outer shell (shell element) 32Intermediate element (shell element) 33Inner shell (shell element) 4Steering spindle 5Support unit 51Fasteners 6Adjustment drive 61Drive unit 62Motor 63Threaded element 64Thrust bearing 65Gear ring 7First spindle drive 71First threaded spindle 72First spindle nut 73Connecting element 8Second spindle drive 81Second threaded spindle 82Second spindle nut LLongitudinal axis SGread axis (spindle axis)

Claims

1. Steering column (1) for a motor vehicle, comprising a jacket unit (3), in which a steering spindle (4) is mounted rotatably about a longitudinal axis (L) extending in the longitudinal direction, and which has at least three casing elements (31, 32, 33), which comprise at least an inner casing (33), an outer casing (31) and an intermediate element (32) arranged therebetween, wherein a motorized adjustment drive (6) acts on the casing elements (31, 32, 33), which has a first spindle drive (7) arranged between the inner casing (33) and the intermediate element (32), and a second spindle drive (8) arranged between the intermediate element (32) and the outer casing (31), the first spindle drive (7) having a first threaded spindle (71) which engages in a first spindle nut (72) and can be driven in rotation relative thereto by a drive unit (61), and the second spindle drive (8) having a second threaded spindle (81) which engages in a second spindle nut (82) and can be driven in rotation relative thereto by the drive unit (61), wherein the first spindle nut (72) and the second threaded spindle (81) are coaxially non-rotatably connected to one another to form a threaded unit (63) which can be driven in rotation by the drive unit (61) and which is axially supported relative to the drive unit (61), wherein the outer casing (31) is held by a support unit (5), characterized in that the drive unit (61) is axially fixedly attached to an intermediate element (32).

2. Steering column according to claim 1, characterized in that the internal thread of the first spindle nut (72) is arranged inside the external thread of the second threaded spindle (81).

3. Steering column according to one of the preceding claims, characterized in that the second threaded spindle (81) is designed as a hollow spindle in which the first threaded spindle (71) can be axially accommodated.

4. Steering column according to one of the preceding claims, characterized in that the threaded unit (63) is formed in one piece.

5. Steering column according to one of the preceding claims, characterized in that the threaded unit (63) is connected to a gear wheel (65) of the drive unit (61).

6. Steering column according to one of the preceding claims, characterized in that the threaded unit (63) comprises a plastic material.

7. Steering column according to one of the preceding claims, characterized in that the first spindle drive (7) and the second spindle drive (8) have threads in opposite directions.

8. Steering column according to one of the preceding claims, characterized in that the first spindle drive (7) and the second spindle drive (8) have different thread pitches.

9. Steering column according to one of the preceding claims, characterized in that a manual steering handle can be attached to the steering spindle (4).

10. Steering column according to one of the preceding claims, characterized in that at least one of the spindle drives (7, 8) is designed to be self-locking.

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